Metering valve

ABSTRACT

A metering valve for precision flow control of fluids is shown having a body with a valve stem in threaded engagement in a valve holding member in the body for advancing and retracting movement to adjust the position of the stem. The body has a bushing or sleeve, preferably of resilient synthetic plastic material interposed between inlet and outlet fluid connections and exposed to the upstream pressure and a portion of the valve stem extends into the sleeve which portion is provided with a tapered helical thread or groove for fluid flow. The pitch of the threads on the threaded portion and the pitch of the tapered helical groove can be the same or slightly different. Provision is made for shut off of flow. The sleeve is preferably of a composition having a reduced coefficient of thermal expansion normal to its axis for use at elevated temperatures.

United States Patent 1191 Moore METERING VALVE Primary Examiner-Amo1dRosenthal 1 C 1 B. M E tN t l [75] mentor g g i gg ss l gsAttorney-Zachary T. Wobensmith, 2nd

[73] Assignee: Moore Products Co., Spring House,

Pa [5 7] ABSTRACT [22] Filed; July 15, 1971 A metering valve forprecision flow control of fluids is shown having a body with a valvestem in threaded en- [21] APPI- N05 162,763 gagement in a valve holdingmember in the body for advancing and retracting movement to adjust theposi- 52 us. c1. 251/121, 138/43 tion of the Stem- The body has abushing 9r sleeve, 51 1m. 01. F16k 47/06, Fl5d 1/10 preferably ofresilient synthetic Plastic material inter- [58] Field of Search251/126, 121, 209; posed between inlet and outlet fluid connections and1 3 3 exposed to the upstream pressure and a portion of the valve stemextends into the sleeve which portion is [56] References Cited providedwith a tapered helical thread or groove for UNITED STATES PATENTS fluidflow. The pitch of the threads on the threaded portion and the pitch ofthe tapered helical groove can 2,324,360 7/1943 Camerota 138/43 be thesame or different. Provision is made for 2,323,115 6/1943 Bryant 138/43shut off of flow. The sleeve 18 preferably of a compos1- 1,754,1384/1930 Agee 251/121 1,918,959 7/1933 Culp 138/43 havmg, a resiucedcoefficlem thermal expanslo 3,176,73 4/1965 McDermott et 8L 251/368normal to its axis for use at elevated temperatures. 2,683,973 7/1954Mettler 138/43 X 4 Cl D 2,568,123 9/1951 Goldberg 138/43 4 Flgures as 934 37 3/ 2 2Q 40 N 25\ t, ,4

PATENTE JAN 1 51974 w mw mw \w nwv QM NM mum \QR MGR ATTORNEY METERINGVALVE BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to metering valves and more particularly to valves foruse with small flows of high pressure fluid with a wide range ofadjustment.

2. Description of the Prior Art It has heretofore been the commonpractice to employ needle valves for the control of small flows butthese are difficult to accurately adjust for close control of smallflows and may clog with very small flows.

It has also heretofore been proposed to control the flow of fluid with avalve having a threaded valve stem for positioning of a head having anintegral internal cylindrical surface movable with respect to a portionof the valve body which has thereon a helical groove of uniform crosssection to vary the length of the helical path through which fluidflows. The structure requires high precision in the manufacture of themating parts and did not permit shut-off.

SUMMARY OF THE INVENTION In accordance with the invention a meteringvalve is provided with which flow can be shut-off and with which controlof small flows of high pressure fluids is effected. The control of rateof flow is effected by movement of a valve stem having a threadedportion for determining the positioning of the valve stem with respectto a sleeve of synthetic plastic material with an interference fit andpreferably having a reduced coefficient of thermal expansion foroperation at elevated temperatures. Provision is also made to eliminateend play or backlash in the valve adjustment.

It is the principal object of the present invention to provide ametering valve which is simple in construction, which has a wide rangeof flow adjustment and which avoids cyclical variation in itsadjustment.

It is a further object of the present invention to provide a meteringvalve which does not require precision manufacture of the parts movablyengaged for flow control. I

Other objects and advantageous features of the invention will beapparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic featuresof the invention will be more readily understood from the followingdescription taken in connection with the accompanying drawings formingpart thereof, in which:

FIG. 1 is a longitudinal sectional view, enlarged, of a metering valve 7in accordance with the invention in shut-off condition; 4

FIG. 2 is a fragmentary view of a portion of the valve with the stem inoperating position for flow at a set level;

FIG. 3 is a transverse sectional view taken approximately in the line3-3 of FIG. 1; and

FIG. 4 is a view in perspective of one end of the valve stem.

It should, of course, be understood that the description and drawingsherein are illustrative merely and that various modifications andchanges can be made in the structure disclosed without departing fromthe spirit of the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularlyto the drawings, a valve body is provided in the form of a block havinga cylindrical interior bore 11 with a shoulder 12 qnd reduced endportion 13 with a terminal wall 14.

A fluid supply passageway 15, communicating with the bore 11, may have afluid supply pipe 16 connected thereto, and a fluid delivery passageway17 terminating at the end wall 14 may have a fluid delivery pipe 18connected thereto.

The bore 11 has axially aligned therewith a threaded portion 20 with anenlarged cylindrical bore 21 outwardly thereof.

A valve stem carrier 24 is provided, preferably of metal, having athreaded portion 25 for engagement with the threaded portion 20 of thevalve body 10 and a hollow cylindrical extension 26 with an end face 27,and an interior bore 29 from which an aligned interior bore 30 extendsoutwardly to an enlarged packing bore 31.

The valve stem carrier 24, outwardly of the threaded portion 25, has agroove 32 for the reception of a packing ring 33 and a hexagonal portion34 for positioning of the carrier 24.

The valve stem carrier 24, beyond the hexagonal portion 34, has athreaded section 35 on which panel mounting nuts 36 are carried and onwhich a gland nut 37 is engaged.

The valve stem carrier 24 has its end face 27 in engagement with a rim40 of a metering sleeve 41. The rim 40 of the metering sleeve 41 has atapered end face 42 which engages a packing ring 43, such as an O-ring,in the bore end portion 13 and holds the packing ring 43 engaged withthe bore end portion 13 and end wall 14 to prevent fluid leakage at thislocation.

The metering sleeve 41 has an inner bore 44, an enlarged end boreportion 45, and an exterior surface 46 of reduced diameter to provide asurrounding space 47 which communicates with the fluid suply passageway48 in the extension 26 of the carrier 24.

The metering sleeve 41 has an opposite end face 49 which terminates inspaced relation from the bore 30, to permit fluid flow.

The metering sleeve 41 is preferably made of resilient synthetic plasticmaterial such as teflon, which may be modified if desired by theaddition of a filler, such as glass fibers, mica, ceramic materials orpolymeric materials, which substantially reduces the coefficient ofthermal expansion radially. Thus the differential thermal expansionbetween the sleeve 41 and the stem portion 65 will be minimized topermit operation at elevated temperatures.

A valve stem is provided, preferably of metal, which may have a knob 56on its outer end for manual turning thereof.

The valve stem 55 extends through the gland nut 37 and has a threadedstem portion 57 which is engaged with an internally threaded nut 58 ofresilient synthetic plastic material which is held by the gland nut 37against a gland packing 59 in the packing bore 31.

The use of a resilient nut 58 affected by adjustment of the gland nut 37avoids lost motion or backlash upon movement of the valve stem 55.

The valve stem 55 has spaced shoulders 61 and 62 with a groove 63therebetween for the reception of a packing ring 64, such as an O-ring,which engages the bore 30 to prevent fluid leakage at this location.

The valve stem 55 has a stem portion 65 extending within the bore 44 ofthe metering sleeve 41.

The stem portion 65 is provided on the exterior thereof with a helicalgroove 66 which commences at its end face 67 and extends toward theshoulder 62. The groove 66 is of decreasing cross section and terminatedbefore it reaches the shoulder 62. The pitch of the groove 66 can be thesame as the pitch of the threads of the threaded portion 57 to avoidcyclical variations upon valve adjustment and also to minimize theabrasion of the sleeve 41 by the stem portion 65.

The stem portion 65 preferably has an interference fit with respect tothe bore 44 to provide a leak-tight fit without the necessity forextreme precision in the manufacture of these parts.

The end face 67 of the valve stem portion 65 has a groove 70 for thereception of a packing ring 71, such as an O-ring, to engage theterminal wall 14 and cut off fluid flow when positioned as shown in FIG.1 but to permit fluid flow when positioned as shown in FIG. 2.

The mode of operation will now be pointed out.

The valve is shown in shut off position in FIG. 1, the packing 71 in thegroove 70 being in engagement with the terminal wall 14 and preventingany flow of fluid to the fluid delivery passageway 17.

Fluid under pressure in the fluid supply pipe 16 and fluid supplypassageway is effective through the passageway 48 and to the space 47where it tends to compress the resilient metering sleeve 41 against themetallic valve stem portion 65. It has been found that by exposing theoutside of the resilient metering sleeve 41 to the upstream pressure thevalve will withstand much higher pressure differential than it will forflow in the opposite direction.

If, now, the valve stem 55 is turned by the knob 56 the packing ring 71will be separated from its seat on the terminal wall 14 (see FIG. 2) andcan be turned to the desired extent to permit fluid flow from the space47 around the end face 49 of the metering sleeve 41 and along the groove66. The flow will be determined by the exposure of a smaller or largercross section of the groove 66 at the upstream end in accordance withthe positioning of the valve stem portion 65 in the metering sleeve 41.

I claim:

1. A metering valve comprising a body having an interior opening withfluid supply and delivery passageways communicating therewith,

a metering member in said opening having a longitudinal bore, 7

a valve stem having a portion extending into said bore,

said metering member being of resilient synthetic plastic material andhaving a sleeve portion on the exterior surface of which pressure insaid fluid supply passageway is effective for compressing said sleeveportion into engagement with said valve stem portion,

said valve stem portion having a helical groove thereon for controllingflow therein as determined by the positioning of said stem portion alongsaid metering member,

said grooved valve stem portion and said metering member having aninterference fit.

2. A metering valve as defined in claim 1 in which said helical grooveis of diminishing cross section between its ends.

3. A metering valve as defined in claim 1 in which said valve stem andsaid body have interengageable portions for shutting off fluid flowbetween said supply and said delivery connections.

4. A metering valve comprising a body having an interior opening wtthfluid supply and delivery passageways communicating therewith,

a metering member in said opening having a longitudinal bore,

a valve stem having a portion extending into said bore,

said stem portion having a helical groove thereon of diminishing crosssection between its ends for controlling flow therein as determined bythe positioning of said stem portion along said metering memher,

said body having mounted thereon a valve stem carrier,

said threaded member comprising an internally threaded nut with whichsaid threaded portion of said stem is in engagement, and

said nut being of resilient plastic material for eliminating backlash.

1. A metering valve comprising a body having an interior opening withfluid supply and delivery passageways communicating therewith, ametering member in said opening having a longitudinal bore, a valve stemhaving a portion extending into said bore, said metering member being ofresilient synthetic plastic material and having a sleeve portion on theexterior surface of which pressure in said fluid supply passageway iseffective for compressing said sleeve portion into engagement with saidvalve stem portion, said valve stem portion having a helical groovethereon for controlling flow therein as determined by the positioning ofsaid stem portion along said metering member, said grooved valve stemportion and said metering member having an interference fit.
 2. Ametering valve as defined in claim 1 in which said helical groove is ofdiminishing cross section between its ends.
 3. A metering valve asdefined in claim 1 in which said valve stem and said body haveinterengageable portions for shutting off fluid flow between said supplyand said delivery connections.
 4. A metering valve comprising a bodyhaving an interior opening wtth fluid supply and delivery passagewayscommunicating therewith, a metering member in said opening having alongitudinal bore, a valve stem having a portion extending into saidbore, said stem portion having a helical groove thereon of diminishingcross section between its ends for controlling flow therein asdetermined by the positioning of said stem portion along said meteringmember, said body having mounted thereon a valve stem carrier, saidthreaded member comprising an internally threaded nut with which saidthreaded portion of said stem is in engagement, and said nut being ofresilient plastic material for eliminating backlash.